Patient-Derived iPSC-Cardiomyocytes Reveal Subclinical Cardiomyocyte Dysfunction Associated With the CAV3 N-Terminal...

The CAV3 p.Ala46Thr mutation is previously associated with skeletal muscle damage only, with its myocardial impact and long-term cardiac risks unclear. This study is aimed at investigating whether it induces subclinical myocardial damage at the cellular level and explore its mechanism using a patient-specific iPSC-CMs model. To achieve this, peripheral blood from a proband carrying the CAV3 c.136G>A (p.Ala46Thr) mutation but only clinical manifestations of skeletal muscle damage was collected. Subsequently, a patient-derived iPSC line was established and directionally differentiated into iPSC-CMs. IF and TEM were then conducted to observe the structure of cardiomyocytes, the arrangement of sarcomeres, and the subcellular localization of CAV3 protein. Additionally, laser confocal calcium imaging technology was used to analyze the basic electrophysiological rhythm of cardiomyocytes and their response to fenoterol. As a result, the mutant iPSC-CMs model was successfully constructed. Compared with controls, mutant iPSC-CMs exhibited a normal cellular structure, but notably, the CAV3 protein exhibited abnormal aggregation around and inside the nucleus, resulting in a loss of membrane localization. Furthermore, functional assays showed that the mutant iPSC-CMs had a significant decrease in basic beating frequency and an irregular rhythm. After stimulation with fenoterol, the increases in beating frequency and rhythm regularity were significantly less pronounced than those in controls. In conclusion, this study is the first to demonstrate that human cardiomyocytes from carriers of the CAV3 p.Ala46Thr mutation without any cardiac symptoms clinically exhibit an abnormal localization of CAV3 protein and definite altered spontaneous activity and calcium-handling behavior. This suggests that the mutation can induce subclinical myocardial damage, and the carriers should be considered as a group with potential risk of heart disease. Overall, this study provides a novel experimental basis for the early warning and accurate treatment of CAV3-related diseases on the site of clinics.